The continual demand for enhanced integrated circuit performance has resulted in, among other things, a dramatic reduction of semiconductor device geometries, and continual efforts to optimize the performance of every substructure within any semiconductor device. A number of improvements and innovations in fabrication processes, material composition, and layout of the active circuit levels of a semiconductor device have resulted in very high-density circuit designs. Increasingly dense circuit design has not only improved a number of performance characteristics, it has also increased the importance of, and attention to, semiconductor material properties and behaviors.
The increased packing density of the integrated circuit generates numerous challenges to the semiconductor manufacturing process. Nearly every device must be smaller without degrading operational performance of the integrated circuitry. High packing density, low heat generation, and low power consumption, with good reliability must be maintained without any functional degradation. Increased packing density of integrated circuits is usually accompanied by smaller feature size and, correspondingly, smaller device geometries.
At the same time, the use of electronic products and systems has spread into a number of new and distinct applications that, until recently, were not associated with electronic technology. Often, such new applications place a number of unique demands on components and substructures. Consider, for example, the radiation tolerance required of satellite or spacecraft systems, or the heat and shock tolerance required of automotive systems.
Thus, optimized performance over a broader range of operating conditions is required of many electronic components and substructures. This has resulted in a number of improvements and innovations in electronic systems, and has increased the importance of, and attention to, component and substructure properties and behaviors.
Commonly, system designers specify or define a number of required operational parameters (e.g., max/min voltage, signal timing) for certain circuitry segments in a system. Semiconductor devices (i.e., integrated circuits) must comply with such required parameters in order to be used in the system. For example, a system may require that a semiconductor device operate over supply voltage range of 0V to 40V, optimized for performance at 20V. In another example, a system may require that a semiconductor device provide a specified timing parameter (e.g., trise(MIN), tfall(MAX)).
Unfortunately, however, there are a large number of variables in semiconductor device manufacturing that can affect any given performance parameter. Intra-process variations, feature matching issues, and layout considerations are among a number of concerns that impact a device manufacturer's ability to provide a specified performance parameter. In some cases, a semiconductor device's standard operational parameters may be sufficient to provide a required performance level in a given system. In a number of other cases, however, a given system may require a very specific or peculiar performance parameter—such that an integrated circuit must be designed specifically for that application, if possible.
Consider, for example, a common low-side driver circuit utilized in a high-voltage application, having specific performance parameters. Depending upon the configuration of the driver circuit, surrounding circuitry, and required performance, a number of design or performance issues may arise. In a number of applications, an output node from the driver circuit can have a very large voltage swing—sometimes exceeding the driver circuit's own supply voltage level. Such excess can cause a voltage feedback condition, conducting charge back into the driver's voltage supply. This causes instabilities in the voltages supply, which degrades system performance and reliability. Furthermore, especially where such circuitry is implemented in high voltage applications, low power consumption is very important—particularly when portions of the driver circuitry may be in a standby (i.e., inactive) mode. Even fractionally inefficient circuitry can result in sizable power consumption during the operational lifetime of a device or system.
To the extent that a particular application may have specific or peculiar design or performance constraints, driver circuitry must further be adapted to address such concerns. Specific signal propagation timings, effective resistance values and other similar concerns can further impact or limit the design of driver circuitry. The same is true of certain semiconductor fabrication technologies. Design layout rules, process tolerances and variations and other similar, technology-specific issues must be comprehended even as the performance and reliability issues outlined above are also addressed.
In approaching these problems, designers using conventional system often address—either by choice or by process-specific limitations—only one or two of the most critical issues during the design of a device, while the remaining issues are left unaddressed. Once a design is complete and a device manufactured, those device may simply be screened or tested for compliance with all parameters. When a device is non-compliant, it is scrapped—degrading yield and increasing costs. Alternatively, designers may produce complicated solutions in an attempt to address all problems and requirements simultaneously. Unfortunately, however, such approaches often requirement substantial modification of or deviation from standard, high-volume semiconductor production processes. Such solutions thus end up being costly and inefficient.
As a result, there is a need for a system for producing high-voltage, low-power driver circuitry that is readily adaptable to address a variety of specific parametric requirements, while providing efficient and reliable device performance in an easy, efficient and cost-effective manner.